}

func NewWalker(context *build.Context, root string) *Walker {
	w := &Walker{
		context:  context,
		root:     root,
		features: map[string]bool{},
		imported: map[string]*apiPackage{"unsafe": &apiPackage{Package: types.Unsafe}},
	}
	w.loadImports()
	return w
}

func (w *Walker) Features() (fs []string) {
	for f := range w.features {
		fs = append(fs, f)
	}